The present application relates generally to systems and methods for seismic exploration, including the acquisition and/or processing of seismic data to estimate properties of the Earth's subsurface.
The principal type of data used to explore for oil and gas resources is seismic reflection data that image subsurface geology. There are three seismic wave modes that can be used for subsurface imaging—a compressional-wave (P) mode and two shear-wave modes (SV and SH). When geophysicists acquire seismic data that have all three of these modes, the data are called full elastic-wavefield data. Full elastic-wavefield data are acquired by deploying three separate orthogonal seismic sources at every source station across a prospect area. One source applies a vertical force vector to the Earth, a second source applies a horizontal force vector in the inline (X) direction, and a third source applies a second horizontal force vector in the crossline (Y) direction.
The wavefields produced by each of these three orthogonal-force sources are recorded by 3-component geophones that have orthogonal (XYZ) sensing elements. The resulting data are called 9-component data because they consist of 3-component data produced by three different sources that occupy the same source station in sequence, not simultaneously. Full descriptions and illustrations of the sources, sensors, and field procedures used to acquire full elastic-wavefield data can be found in Chapter 2, Multicomponent Seismic Technology, Geophysical References Series No. 18, Society of Exploration Geophysicists, authored by B. A. Hardage, M. V. DeAngelo, P. E. Murray, and D. Sava (2011). Vertical, single-component, surface-based geophones are used for the purpose of acquiring P-wave seismic data